A third of Liberal Democrat MPs who voted on the Human Fertilisation and Embryology Bill in the Commons yesterday opposed it.
In 2005 the party made a manifesto commitment to end discrimination against lesbians seeking fertility treatment.
Lib Dem MPs had a free vote on the legislation, which will make it easier for lesbians and single women to access NHS fertilisation services and allows a lesbian or gay couple to be named on the birth certificate as the legal parents of their children.
The bill also contains provisions to allow the creation of human-animal embryos, from which stem cells can be harvested, but they must be destroyed after 14 days.
Yesterday MPs voted 355 to 129 for the bill.
Among the 16 Lib Dems who voted against were ten frontbenchers including Vince Cable, Steve Webb, and Sarah Teather, former leader Charles Kennedy and former deputy leader Alan Beith.
“We believe strongly in an individual’s right to live their lives as they see fit, without discrimination, with personal privacy, with equal rights in front of the law and the opportunities to make the best of their talents,” he said.
“This applies to a person’s sexuality and gender identity in the same way it does to their race, gender, or religion.
“The Liberal Democrats have been consistent in our application of these principles and are proud of our track record on issues relating to lesbian, gay, bisexual and transgender rights.”
30 Lib Dems voted in favour of the legislation, including leader Nick Clegg, Simon Hughes and Chris Huhne.
In the Lib Dem general election manifesto for the 2005 general election the party pledged to “repeal provisions in the Human Fertilisation and Embryology Act which discriminate against lesbian couples.”
Tory MPs also had a free vote on the bill, and 49 of them voted in favour, among them party leader David Cameron, George Osborne, Oliver Letwin, Malcolm Rifkind, Grant Shapps, Andrew Lansley, Theresa Villiers, Ken Clarke, Michael Howard and Jeremy Hunt.
84 Tory MPs voted against the legislation.
16 Labour MPs rebelled against a three line whip to vote against, among them former Cabinet minister Ruth Kelly.
Bob Spink, UKIP’s only MP, voted for the bill, as did two Plaid Cymru MPs. Four SNP MPs voted against and two voted in favour.
4 DUP and 3 SDLP MPs voted against the bill.